A064787 - OEIS

A064787

Inverse permutation to A053212.

1, 2, 3, 4, 6, 5, 11, 7, 8, 9, 23, 10, 31, 15, 13, 12, 58, 14, 74, 16, 18, 29, 122, 17, 25, 40, 21, 22, 224, 19, 267, 20, 38, 69, 33, 24, 453, 89, 49, 26, 636, 28, 737, 43, 30, 141, 995, 27, 53, 35, 84, 57, 1523, 34, 59, 36, 108, 257, 2244, 32, 2528, 310, 41, 37, 77, 52

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OFFSET

1,2

COMMENTS

a(n) is the index of A005179(n) in A007416; equivalently, a(n) is the number of minimal numbers (numbers in A007416) that are <= A005179(n). - Jianing Song, Aug 16 2022

LINKS

Table of n, a(n) for n=1..66.

Index entries for sequences that are permutations of the natural numbers

EXAMPLE

a(23) = 122 because d(n) (A000005(n)) takes 121 different values before it first reaches 23 (at n = 2^22).

PROG

(Haskell)

import Data.List (elemIndex); import Data.Maybe (fromJust)

a064787 = (+ 1) . fromJust . (`elemIndex` a053212_list)

-- Reinhard Zumkeller, Apr 18 2015

CROSSREFS

Cf. A053212, A005179, A007416, A000005.